Polycystic kidney disease is classified into ADPKD (autosomal dominant polycystic kidney disease) and ARPKD (autosomal recessive polycystic kidney disease). In both types of polycystic kidney disease, many cysts develop in the cortex and medulla of the kidney, leading to kidney dysfunction accompanied by substantial atrophy and fibrosis. As the disease progresses, the kidneys develop hypertrophy, leading to kidney failure requiring dialysis.
In cyst epithelial cells wherein cysts develop from tubular cells, cyclic AMP (cAMP) activates protein kinase A (PKA), and a series of MAP kinase (MAPK) pathways are activated to induce cell proliferation. In the cyst epithelial cells, the expression of vasopressin receptor (V2R) is enhanced and adenylate cyclase activity is elevated, which further increases cAMP levels and accelerates cell proliferation.
Vasopressin receptor antagonists have been reported to have complete response in animal models of polycystic kidney disease, and tolvaptan is advancing in clinical trials (see, for example, Patent Literature (PTL) 1 and Non-patent Literature (NPL) 1, 2, and 3). Octreotide, which is a somatostatin derivative that suppresses adenylate cyclase activity, is also expected to be useful as an agent for treating ADPKD, and clinical test results therefor have recently been reported (see Non-patent Literature (NPL) 4).